The present invention relates to a computerized system for scheduling work orders for manufacturing products in a manufacturing process.
Prior to the introduction of computerized scheduling systems, the scheduling of work orders in a manufacturing facility was performed manually. The person responsible for determining the work schedule manually assigned the work to be performed to specific dates. The manual scheduling process involved determining what work has to be performed and the time, materials, and resources (i.e., machines, workers, tools, etc.) required to perform it, as well as other information which influenced the schedule, such as which work was more important than other work. This process is costly, very tedious and often inaccurate. The frequency with which the scheduling process must be performed contributes to the difficulty of obtaining timely, accurate manual scheduling.
As commercial computer systems became available, manufacturers began using computerized systems that assisted in the storage and retrieval of information relevant to the scheduling of work in a manufacturing facility. In the late 1950's and during the 1960's, efforts were made to implement Material Requirements Planning or MRP. MRP was limited in scope to dealing only with material requirements (i.e., which parts or materials were needed and when). These early computerized systems were not capable of scheduling operations based upon the availability of materials or resource capacity.
During the 1970's and 1980's, many commercially available systems were created which provided more comprehensive MRP, and it was eventually renamed Manufacturing Resource Planning. The new MRP dealt with additional problems, such as forecasting, inventory management, shop floor control, engineering, and change management. Some of these systems dealt with the capacity of the plant to perform the work. One such approach was called rough-cut capacity planning and, as the name suggests, it provided a crude estimate of the capacity needed to satisfy work requirements. Rough-cut capacity planning determined the capacity needed, but was not capable of scheduling work orders based on capacity limits.
Other systems for scheduling work orders in a manufacturing facility relied on a method of scheduling that compared the total hours of capacity to the total hours of load from operations. Such systems were not capable of "event-oriented" scheduling, i.e., assigning a particular event or operation to a particular resource for a particular time period.
It was not until the mid-1980's that a computerized event-oriented scheduling system was developed that was capable of scheduling work orders and the operations required to carry out the work orders, taking into account the finite capacity of the various resources needed for the manufacturing process, i.e., finite scheduling. ProfitKey, a New Hampshire-based company, developed one of the first such finite scheduling systems available to the market. Using the ProfitKey scheduler, a manufacturer could determine the start and finish date of work orders and their operations based upon resource capacity and availability. A similar system was developed by Lilly Software Associates, Inc. and marketed as part of the VISUAL Manufacturing.TM. system beginning in early 1993.
However, neither the ProfitKey system nor the early 1993 version of the VISUAL Manufacturing.TM. system was capable taking the availability of materials into account in determining the scheduling of work orders. In addition, the ProfitKey system and the early 1993 version of the VISUAL Manufacturing.TM. were both limited to a single resource capacity calendar for all resources in the system, and neither system was capable of generating multiple schedules based on different assumptions regarding resource capacity for individual resources. Further, the ProfitKey system was not capable of scheduling multiple dissimilar resources concurrently based upon user specifications.
Other scheduling systems include Microsoft Project.TM. and Norton's Timeline from Symantec. These programs are capable of storing and retrieving information about a project defined by the user using a method consistent with Critical Path Method (CPM) theory. These tools are designed to handle projects that have definable events that are interdependent, similar to a single work order in a manufacturing process. These systems are not, however, capable of managing hundreds of work orders at a time as is typical in most manufacturing plants.
No prior art system. is capable of scheduling a plurality of work orders or operations in a manufacturing facility, using a finite, event-oriented scheduling process with the added feature of taking into account the availability of materials that are used in the manufacturing process.